Abstract: A control circuit for a MOSFET used in a synchronous rectification circuit applies a gate voltage to the MOSFET during most of a period in which a current flows in a MOSFET. As a result, conduction loss is decreased, making it possible to increase device efficiency and form a device that is compact and lightweight.

Abstract: A control circuit for a MOSFET used in a synchronous rectification circuit applies a gate voltage to the MOSFET during most of a period in which a current flows in a MOSFET. As a result, conduction loss is decreased, making it possible to increase device efficiency and form a device that is compact and lightweight.

Abstract: A DC/DC converter converts a voltage of a DC power supply to another DC voltage by switching on and off a switching element, which determines an oscillating period and a forced stop period of the switching element based on a comparison signal obtained by comparing an output of an output-voltage detecting and adjusting circuit, which controls the output of the DC/DC converter at a certain voltage, and an output of a triangular-wave generating circuit in a second comparator. The DC/DC converter facilitates confining the pulsation of the output voltage of the DC/DC converter caused by the maximum load in the state of light load including the state of no load, within an allowable range.

Abstract: In a DC/DC converter including a half-wave rectifying circuit of a diode and a capacitor for rectifying a voltage occurring on a secondary side of an insulated transformer, an ON period of one of switch elements has a fixed duration, permitting control of an ON period of the other switch element in order to achieve a constant DC output voltage. Since the switching frequency varies only during the ON period of the controlled switch element, an increase in switching frequency is restrained during a period in which the circuit carries light loads.

Abstract: The present invention controls reactive current to be low so that expensive components are not required and costs are decreased. According to the present invention, serial circuits of two switching elements are connected between the positive and negative electrodes of a DC power supply, a tertiary winding 6 and a quaternary winding are added to a transformer of a DC/DC converter where a serial circuit of a capacitor and a transformer primary winding are connected to the switching element in parallel, an ON/OFF signal is applied to the switching element via the tertiary winding, the quaternary winding becomes a winding for the power supply of a control circuit, the timing of the switching of the positive/negative of the quaternary winding voltage is detected by this control circuit, and an ON/OFF signal is applied to the switching element at this timing. By decreasing the ON time of the switching element, the reactive current can be decreased.

Abstract: The present invention controls reactive current to be low so that expensive components are not required and costs are decreased. According to the present invention, serial circuits of two switching elements are connected between the positive and negative electrodes of a DC power supply, a tertiary winding 6 and a quaternary winding are added to a transformer of a DC/DC converter where a serial circuit of a capacitor and a transformer primary winding are connected to the switching element in parallel, an ON/OFF signal is applied to the switching element via the tertiary winding, the quaternary winding becomes a winding for the power supply of a control circuit, the timing of the switching of the positive/negative of the quaternary winding voltage is detected by this control circuit, and an ON/OFF signal is applied to the switching element at this timing. By decreasing the ON time of the switching element, the reactive current can be decreased.

Abstract: A DC/DC converter converts a voltage of a DC power supply to another DC voltage by switching on and off a switching element, which determines an oscillating period and a forced stop period of the switching element based on a comparison signal obtained by comparing an output of an output-voltage detecting and adjusting circuit, which controls the output of the DC/DC converter at a certain voltage, and an output of a triangular-wave generating circuit in a second comparator. The DC/DC converter facilitates confining the pulsation of the output voltage of the DC/DC converter caused by the maximum load in the state of light load including the state of no load, within an allowable range, and reducing the switching and conduction losses.

Abstract: In a DC/DC converter including a half-wave rectifying circuit of a diode and a capacitor for rectifying a voltage occurring on a secondary side of an insulated transformer, an ON period of one of switch elements has a fixed duration, permitting control of an ON period of the other switch element in order to achieve a constant DC output voltage. Since the switching frequency varies only during the ON period of the controlled switch element, an increase in switching frequency is restrained during a period in which the circuit carries light loads.

Abstract: A diode bridge is connected to an AC power supply, and a series circuit comprised of a reactor and a main MOSFET is connected parallel to an output terminal of the diode bridge. A source terminal of an auxiliary MOSFET is connected to a drain terminal of the primary MOSFET to form a MOSFET series circuit. The MOSFETs are alternately turned on and off to allow capacitors connected parallel to the MOSFETs to perform charging and discharging operations. Thus, gentle voltage waveforms are generated when the MOSFETs are turned on and off, thereby reducing switching loss and noise.

Abstract: A rotary turbine fluid pump employs unique configurations of turbine vane receptacle opening and turbine vanes. The turbine vane receptacle is connected to a circumferentially extending fluid path, in which free ends of turbine vanes are inserted for pressurization of the fluid therein. The turbine vane receptacle operation has pair of surfaces opposing and spaced apart to each other. Each surface is radially tapered toward the center at a first inclination rate. Each turbine vane is provided edges opposing the surfaces of the turbine vane receptacle operation. The edges are correspondingly tapered at a second rate which is determined so that the spacing between the surface and the edge is gradually increased toward the rotation center of the turbine. This construction minimizes friction increasing when the pressure balance in floating seal formed between the surface and the edge is destroyed.